|“||In that case, maybe I should try being a little more direct. Well? Can you hear what my heart is saying? Yuzu, inside of me, when it concerns my feelings for you, I have a part that's "good", but also a part that's "bad". Knowing that, do you still want to take a peek inside of me?||”|
Mei is a teenager with straight silky black hair that goes beyond her shoulders. She also has purple eyes. Whilst in school she dresses formally in the uniform, and wears a wrist band on her right arm. When attending events outside of school, she wears plain ordinary clothes which attract little attention to her. she starts wearing a ring that Yuzu gave to her but only wears it outside of school.
On her exterior, Mei appears to have a cold and ruthless attitude towards her peers. She's obtained a stern and short-tempered personality from her father abandoning her. She is unable to communicate with Yuzu normally and struggles to convey her feelings properly, this results in her often making frequent sexual advances towards Yuzu. Despite how she acts, on the inside she is sensitive, broken and lonely. Her usually hard personality contrasts with her emotional side, which manifests often. Mei struggles to understand Yuzu's optimistic nature, as it harshly mirrors her pessimistic one. As the series progresses she slowly changes being less cold to Yuzu and a little bit more caring towards her. Although she still has a hard time being honest and understand on what she's feeling. She does have a bit of a soft spot, she likes teddy bears. She's more confident than Yuzu knowing the fact that not everyone will approve of their relationship.
Yuzu is Mei's new stepsister, who is a month older than her. At first, Mei sees Yuzu only as a nuisance and makes in the hopes of shutting her up and repelling her away, yet begins to become attracted to Yuzu's brash personality. In later chapters, Mei appears to be reciprocating Yuzu's romantic feelings to some degree, becoming rather possessive of her due to Matsuri's advances on Yuzu opening up to her, and feeling guilty when she believes Yuzu is troubled or sad because of her actions, She expresses to Matsuri she's thankful for having met Yuzu. However she completely rejects Yuzu when she wants to confess, as Yuzu didn't infere her feelings clearly enough for Mei to understand. The two are currently dating.
Mei's father, who also played the part of her sensei and role model. She aspired to be just like him. After he left home to travel, the burden of taking care of the school in his absence was lain upon her shoulders, and she hoped he'd return to become the principal after her grandfather. However, she realized he didn't want that anymore, and started to distance herself from him. She has an habit of calling him "sensei", as he was more of a teacher to her than a father, which annoys him.
Mei looks up to her grandfather. After he was hospitalized, she decides to take on his workload on her own, which, along with her work at the Student Council president, causes severe stress and fatigue to her. When Mei and Yuzu kiss in the chairman's office, Mei puts his portrait face down as a sign of respect to him.
Yuzu's mother immediately accepted Mei into their family, and treats Mei no different to how she treats Yuzu. Yuzu's mother genuinely cares and worries for Mei, and as a result Mei has taken a liking to her.
Himeko is Mei's vice-president in the Student Council and her childhood friend. When they were younger, they used to play with each other, but after Mei's father left, she started to distance herself from Himeko, starting to see her as a nuisance rather than a friend, but Yuzu helped them rekindle their friendship. Mei is the subject of Himeko's affections, but these emotions are not reciprocated.
Harumi is Yuzu's best friend, but she and Mei rarely interact, so their relationship is unknown.
Glasses-Senpai is a fellow member of the school council as well as Mei's second vice president. They are on friendly terms with one another and often work together to reprehend delinquents like Yuzu.
Mei's first encounter with Matsuri was witnessing her kiss Yuzu. This leads her to develop and instant dislike of Matsuri, who threatens Mei to leave Yuzu alone. Mei notes that the two of them aren't so different. Matsuri realizes that Mei never wanted to take Yuzu from her and realized even Mei cares for her feelings too, all conflict gets resolved and eventually Matsuri stopped thinking about her as a rival and starts seeing Mei as another older sister. they both get along as Yuzu's younger sisters. Mei s tutor's Matsuri with studies from time to time.
They dated for only a short period of time, but they quickly broke up after Sara found out the connection between Mei and Yuzu. Mei later apologized to Sara, saying she was just using her, but Sara said she'd forgive her if she and Yuzu held hands on the way back home, which they did.
They never directly interacted, but Nina tried to keep Yuzu from intruding in her relationship with Sara, if only for the sake of Sara's happiness.
Mei appears to respect Mitsuko a lot, even though Mitsuko scolds Mei due to Yuzu's breaking of the rules.
- (To Yuzu) "Living by the rules of the school prepares you for society. We are all under the same conditions, so if you want to go to this school, you will abide by the school's regulations!" 
- (To Matsuri) "The Two of us aren't so different. My whole live I've desired affection from others, I felt bitter to the people around me and I closed off my heart, and a heart that lets nothing in... will become empty before you realize it. But, in this world, you'll sometimes meet meddlesome people who will, even without asking, give you the love you need. And for someone like you or me, meeting such a person is very blissful." 
- (To Yuzu) "In that case, maybe I should try being a little more direct. Well? Can you hear what my heart is saying? Yuzu, inside of me, when it concerns my feelings for you, I have a part that's "good", but also a part that's "bad". Knowing that, do you still want to take a peek inside of me?" 
- "Mei" (芽衣?) is a feminine Japanese name, with multiple meanings depending on the kanjis used. The specific kanjis of her name mean "sprout, garment" or "bright, reliant".
- "Aihara" (藍原?) means "indigo field".
- Mei is not very good at sewing.
- Mei likes bears.
- Mei's ears are sensitive.
- Mei is also not tickilish as yuzu found in Citrus +5.
- As shown in Citrus +2 Mei has a scar on her right thigh from elementry school.
- The small stuffed bear keychain given to her by Yuzu is called Anthoniko, while the big one given to her by Shō is called Kumagorō. She also has another yellow bear from a claw game that Yuzu won for her.
- ↑ 1.0 1.1 Citrus Manga Chapter 12, pages 34-36
- ↑ Citrus Manga: Chapter 7
- ↑ Citrus Manga: Chapter 20, page 39-40
- ↑ Citrus Manga Chapter 7, pages 19-20
- ↑ Citrus Manga Chapter 12, pages 26-28
- ↑ Citrus Manga Chapter 12, pages 29-30
- ↑ Citrus Manga Chapter 15, pages 13-13
- ↑ Citrus Manga Citrus+ 4, pages 4-9
- ↑ Citrus Manga: Chapter 1, page 8
- ↑ Citrus Manga: Chapter 12, pages 26-27
- ↑ Citrus Volume 1 Extras